What Is ARPANET and Why Is It Significant?

ARPANET, or Advanced Research Projects Agency Network (ARPANET), is the pioneering public packet-switched computer network in the United States. Primarily intended for academic and research endeavors. It marked a significant milestone in the history of computer networking.

What is Arpanet

One important thing about this first wide-area packet-switched network is that it played a crucial role in modern computer networks.  It served as the testing ground for numerous protocols widely used today. 

As the prototype of the old internet, its pioneering contributions have had a profound and lasting impact on the evolution of network technologies.

How is ARPANET Related to the Internet?

ARPANET set down the groundwork for everything we do online today! It is like the grandparent of the Internet. It was the first-ever computer network that connected different computers together. 

The scientists and researchers created ARPANET to share information and work together. Over time, they developed new ways for computers to talk to each other, called protocols. These protocols became the foundation of the Internet we use today.

The present Internet technology is a massive global network that allows billions of people to connect, share information, and communicate with each other. So, without ARPANET, there would be no Internet as we know it now.

What is ARPANET Used For?

ARPANET was used to connect computers together so that scientists, researchers, and students could share information and work together more easily. It allowed them to send messages, share files, and access resources from other connected computers.

Before ARPANET, computers mostly worked in isolation, but with this network, they could communicate with each other no matter where they were located. 

This was a big breakthrough because it laid the foundation for today’s Internet. The ideas and technologies developed in ARPANET eventually evolved into what we now use as the Internet.

Who Created ARPANET? 

ARPANET was created by a group of smart scientists and researchers from the U.S. government, led by DARPA. They wanted to create a better way for computers to share information and work together. They devised special rules and protocols for the computers to talk to each other.

 On September 2, 1969, they successfully connected the first two computers on ARPANET. Later, kept adding more computers, and over time, it became the Internet, connecting people and information from all around the world. 

How Did ARPANET Work?

Here’s how ARPANET Works:

  • Connecting Computers: ARPA connected several computers at different locations, like universities and research centers, using special high-speed communication lines. These lines acted like the “roads” that allowed data to travel between the computers. 
  • Packet Switching: Instead of sending information as one big piece, ARPANET used a clever technique called “packet switching.” It broke the data into smaller parts called “packets.” Each packet contained a piece of information, the address of the destination computer, and other control information.
  • Sending Packets: When you wanted to send a message or data to another computer on ARPANET, your computer would divide it into packets. Each packet would then travel independently through the network to reach the destination.
  • Routing Packets: The packets didn’t always take the same path. The network had special devices called “routers” that looked at the destination address on each packet and decided the best route for it to reach the target computer. Sometimes, packets could take different paths to avoid traffic or network issues.
  • Reassembling Packets: Once all the packets reach the destination computer, it reassembles them correctly to recreate the original message or data. It was like putting together the pieces of a puzzle.
  • Collaborative Network: The whole network was designed to be robust. If one connection or computer failed, the packets could still find alternative routes to reach their destination. 

What is the Difference Between the Internet and ARPANET?

The Internet and ARPANET differ significantly in size, purpose, technology, accessibility, services and applications, and user interface.

ARPANET was a small network connecting limited computers for military and research purposes, using basic communication protocols and limited accessibility.

 In contrast, today’s internet is a massive global network connecting billions of devices worldwide, accessible to almost everyone, with advanced technologies, and diverse services like web browsing, email, video streaming, online gaming, social media, and much more.

Suite of Protocols Used

ARPANET used these key protocols to facilitate communication and data transfer between computers. 

  1. NCP (Network Control Program): NCP was one of the earliest protocols used on ARPANET. It allowed different host computers to establish connections and exchange data packets.
  2. IMP (Interface Message Processor): The IMP was a crucial device used in the early ARPANET. It acted as a gateway between the host computers and the network, handling the routing of data packets.
  3. TCP (Transmission Control Protocol): TCP was later developed to replace NCP. It became the foundation of modern Internet communication. TCP ensures reliable data transmission by dividing information into packets and reassembling them at the destination.
  4. IP (Internet Protocol): IP is responsible for the addressing and routing of data packets across the network. 

The combination of TCP/IP became the most essential and widely used protocols that laid the groundwork for today’s internet.


ARPANET laid the groundwork for the modern internet. It connected computers at different places and allowed them to talk to each other. This technology split information into smaller pieces and sent them through the network independently. ARPANET played a crucial role in developing the modern internet, changing how we communicate, share information, and use technology worldwide.

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